The basic concept of Software Radio is that software might realize as many as possible functions after a general hardware platform had been established. It is the heart of Software Radio that A/D and D/A converters with wide band are moved to antennas as near as possible, and high-speed and real time DSP/CPU chirps rather than traditional ASIC will complete the work before D/A and after A/D, and software defines as many as possible the functions of wireless telecommunication.
Firstly, the technologies of intermediate frequency (IF) receiver were researched, which concrete contents included the Software Radio’s structure with low pass sampling for RF signals, one with band pass sampling for RF signals, with band pass sampling for IF signals, the important models for IF signals, and The technologies of applicable platforms. Secondly, the technologies of automatic recognition of modulation schemes were researched, which concrete contents included its application fields, oriented-demodulation automatic recognition of modulation schemes, and the extraction methods of characteristic parameters. Thirdly, the technologies of digital signal processing were analyzed, which main contents included filtering to separate a few channels, carrier synchronization, bit synchronization, modulation by software, and demodulation by software. Finally, the random signal processing technologies were discussed for Software Radio, which main contents involved the design in the time and Z field of Wiener filter, the design of Kalman filter, non-parameterized spectrum estimation, parameterized spectrum estimation, high-order statistic analysis, Fourier transiformation, Fourier transformation of short time, Gabor transformation, and wavelet analysis.
Analyzing the features and development level of FPGA and DSP, it was pointed out that the plan with FPGA plus DSP was more suitable for the demands of the applicable systems of Software Radio.
An algorithm named oriented-demodulation automatic recognition of modulation schemes was suggested. Recognition of modulation schemes relating to demodulation, the correct recognizing rate might be raised, and its processing efficiency might be developed.
A new digital PLL, which was applied to carrier synchronization of a telecommunication system, was researched. In comparison with the traditional PLL, it added a branch with FFT, frequency estimation, and the conversion of frequency into voltage; its capture time was shortened; its synchronous frequency range approximately increased.
The bit synchronization method based on PWM was demonstrated. It employed PWM technology indirectly to insert a bit synchronization signal. Even though symbols was single polar and continuous, the method would accomplish bit synchronization.